They found some "quite pure … high quality" ecstasy, as well as cocaine and ketamine.

More troubling, though, was the discovery of two highly toxic chemicals, including the "absolutely lethal" N-Ethylpentylone (ephylone), which is responsible for a number of mass overdoses around the world.

STA-SAFE member and emergency doctor David Caldicott said ephylone is a stimulant that can cause circulation problems, lethal heart palpitations and hallucinations that can cause dangerous behaviour.

He said the two lethal substances were found inside clear capsules and were both disposed of immediately.

The two people who bought the capsules were "extremely grateful" that the toxic substances were found, he added.

The crew at the medical tent were inside all day, offering consultations on drug use for 128 people, ranging in age from 17 to over 40.

But Dr Caldicott said the environment in which testing took place was "quite harsh" and that "direct measurements of purity were not possible with the equipment".

He advocated for further testing of the samples taken at the festival in laboratories with more "sensitive" machines.

Dr Caldicott said five people used the bin provided by the medical tent to get rid of their drugs, but said between 10 and 20 per cent said they were considering binning it.

"Certainly more than that were convinced that it would alter the way they would consume drugs on that day," he said.

People who utilised the pill testing were given armbands to show that they had done so, but none of the 86 people treated by first-aid workers were wearing them, according to the ambulance commander on Sunday.

Toby Keane said the vast majority of people who were treated on the day were under the influence of drugs or alcohol.

He said that two people were taken to hospital for "acute intoxication", but neither of them were wearing the armbands.

Mr Keane said the number of people treated was on par with previous years.

New drugs detected

Pill testers discovered "a couple of new drugs" being circulated in the ACT.

ACT Chief Health Officer Paul Kelly said that was invaluable information for health authorities and police.

"The ACT Government still believes that not taking any drugs is the message we are giving to people and certainly that was the message given to everyone taken into the tent yesterday, but what we've seen yesterday is a different approach," he said.

Dr Kelly said the trial results would be examined before decisions were made about its continuation.

He said he would be "open to discussions" with other jurisdictions and hoped they would follow suit, but admitted the process involved navigating "complex" health and legal issues.

Tent hard to find, concerns about police

Canberrans who attended the festival said they had difficulty finding the pill-testing tent, which was located in the first-aid area.

One arrest made over 18 tablets

"There needed to be more information about what was happening and how our privacy would be protected," she said.

ACT Chief Police Officer Justine Saunders reiterated that the focus was on the criminal activity of selling and trafficking drugs, rather than possession.

"Let's be honest, this isn't new," she said.

"We've had drug-testing capabilities and drug-injecting rooms around the country for many years and we don't have police standing outside those locations. We didn't have police standing outside this location either."

Only one adult was arrested for drug offences, but they were in possession of 18 ecstasy tablets, as well as some powder.

Another young person was directed into a drug diversion program for being in possession of drugs.